Mesostructured cellular foam silica materials for laccase immobilization and tetracycline removal: A comprehensive study

Authors:

• Jakub Zdarta,
• Agnieszka Ewa Feliczak-Guzik,
• Katarzyna Siwińska-Ciesielczyk,
• Izabela Justyna Nowak,
• Teofil Jesionowski

Abstract

Due to its exceptional textural, morphological and mechanical properties, mesostructured cellular foam (MCF) silica is a suitable support material for enzyme immobilization. However, the simple and efficient protocol of enzyme immobilization using MCF is often overlooked. Thus, in the presented study, we describe the synthesis, modification and characterization of mesostructured cellular foam silica for use in laccase immobilization. It has been established that the synthesized materials are characterized by high surface area equal to approx. 550 m2 g−1 and pores with diameters of approx. 20 nm, which makes them suitable for effective enzyme binding. Furthermore, immobilization of the laccase onto both, unmodified and Cu-modified MCF has been carried out, resulting in process yield of over 95% and 85%, respectively. Upon immobilization, irrespectively of the support used, laccase retained higher activity (over 80%) at a wider temperature (20–40 °C) and pH (4–7) range, as compared to the free enzyme, which exhibited such high activity only at pH 5 and 30 °C. In addition, the reusability of the laccase immobilized onto MCF + Cu material has also been improved as it still retained approx. 90% of its initial activity after 10 reaction cycles. Finally, the obtained biocatalytic systems have been applied for degradation of tetracycline from aqueous solutions resulting in 100% removal of the antibiotic by the MCF + Cu + lac system due to simultaneous adsorption and biocatalytic conversion